How much caffeine is in a Coca-Cola?

A 355 ml (12 fl oz) can holds about 34 mg of caffeine — roughly 9.7 mg per 100 ml, so about 32 mg in a 330 ml can. That’s around a third of a café espresso, and nearly three times less than a can of Red Bull.

The most counter-intuitive fact on this page fits in one line: Diet Coke holds more caffeine than the classic.

Variant	Per 100 ml	330 ml can	355 ml can
Coca-Cola Original	~9.7 mg	~32 mg	~34 mg
Coke Zero Sugar	~9.7 mg	~32 mg	~34 mg
Diet Coke	~13 mg	~43 mg	~46 mg
Caffeine-free variants	0 mg	0 mg	0 mg
Fanta, Sprite, lemonades	0 mg	0 mg	0 mg

Figures published by Coca-Cola, checked in August 2026. Recipes vary by country and change over time: the label on your can stays the reference.

Why Diet Coke holds more

Because it isn’t “the classic without the sugar.” Diet Coke is a separate recipe, formulated independently in the 1980s with its own flavour profile — and a higher caffeine dose, around 13 mg per 100 ml against 9.7 mg.

Coke Zero Sugar, by contrast, is built to taste like the original. Which is why it carries the same amount.

So if you drink Diet Coke assuming it’s the lighter option across the board, that holds for sugar and fails for caffeine: one can of Diet Coke is worth roughly one and a third cans of the classic.

“Zero sugar” doesn’t mean “zero caffeine”

This is the most common mix-up, and the naming encourages it. Taking the sugar out doesn’t take the caffeine out: Coke Zero Sugar has as much as the original.

There is a genuinely caffeine-free variant in the range — it’s labelled as such on the pack, and it’s the only decaffeinated one. If caffeine is what you’re avoiding, that’s the one to look for, not the sugar-free.

For context, non-cola soft drinks — Fanta, Sprite, lemonades — contain none at all. Caffeine in a soft drink is almost always a sign that it’s a cola.

Where does the caffeine come from?

It’s added to the recipe as an ingredient, and listed as one on the label. That surprises people: the caffeine in a modern cola doesn’t come from a plant present in the drink, unlike coffee or tea, where it’s extracted from the bean or the leaf.

One practical consequence: the amount is decided, so it’s constant and known. Where a coffee swings from 60 to 80 mg depending on the blend and whoever pulled it, a can of Coke always holds the same thing.

What does 34 mg look like next to everything else?

Drink	Caffeine
Coca-Cola, 355 ml can	~34 mg
Diet Coke, 355 ml can	~46 mg
Brewed black tea, 240 ml	40–70 mg
Café espresso	60–80 mg
Red Bull, 250 ml	80 mg
Filter coffee, 240 ml mug	80–120 mg

A Coke sits at the bottom of the scale: it takes about two and a half cans to match a single café espresso. That’s also why it carries no “high caffeine content” statement — EU rules only require one above 150 mg per litre, and a cola runs around 97 mg per litre. Red Bull, at 320 mg per litre, carries it.

When the figure genuinely matters

A third of a coffee per can isn’t much for an adult. It’s considerably more when the person weighs 25 kg.

France’s ANSES estimates that 11% of 3- to 10-year-olds exceed the threshold for developing a tolerance to caffeine — and at that age it obviously isn’t coming from coffee, but from soft drinks, chocolate and iced teas. Two cans in a day is 64 mg in a body that registers the same dose far more strongly than an adult’s. The agency’s positions are covered in what ANSES says about caffeine.

This isn’t a warning so much as an order of magnitude: the same number doesn’t mean the same thing depending on who drinks it.

What to take away

About 34 mg per can, a third of a coffee. Zero Sugar holds the same, Diet Coke holds more (~46 mg), and only the explicitly caffeine-free variant holds none.

It’s one of the few drinks whose content is perfectly stable, because the caffeine is added rather than extracted. To place the can against everything else you drink, the full table is in caffeine content by drink, and the daily reference point is in how much caffeine per day.

CaffIQ counts cans alongside cups. That’s often where a day is decided: three coffees get noticed; three coffees and two Cokes, much less so.

CaffIQ provides general estimates, not medical advice. For any health question, talk to a qualified professional.